High-resolution measurements of the ν2 and 2ν2-ν2 bands of SO2

Infrared measurements have been made on SO₂ between 450 and 602 cm⁻¹ with a resolution of 0.005 cm⁻¹. The B-type bands due to the bending mode transitions 010-000 and 020-010 have been assigned and analyzed for the ³²S¹⁶O₂ molecule. A total of 3007 transitions were measured and fit for ³²S¹⁶O₂ with a standard deviation of 0.0004 cm⁻¹. Ro-vibrational constants are given that fit the current measurements and the pure rotational transitions reported in the literature.     

Analysis of the Vibrational-Rotational Structure of 2ν1, ν1 + ν3, and 2ν3 Bands of the D2Se Molecule

The absorption spectrum of the D₂Se molecule in the region of 2₁, ₁ + ₃, and 2₃ absorption bands is registered with a high-resolution Fourier spectrometer and is studied theoretically for a Hamiltonian model with allowance for resonant interactions among (200), (101), and (002) vibrational states.     

Dissociation energy of diatomic molecules — comment on the work of Kaur and Mahajan

When observed spectrum of a diatomic molecule is expressed in terms of the Dunham coefficients Y ₀₀, Y ₁₀, Y ₂₀, Y ₀₁ and Y ₁₁ only, dissociation energy of the molecule is given by Y ₀₀+Y ₁₀ ² /(−4Y ₂₀). Kaur and Mahajan [1] have used the Dunham coefficients Y ₁₀, Y ₂₀, Y ₀₁, and Y ₁₁, for 15 vibrational states of 12 diatomic molecules (Y ₀₀ is zero for the cases accounted for), but their dissociation energy cannot be reproduced by the expression Y ₁₀ ² /(−4Y ₂₀). Probable reason for the discrepancy has been discussed.     

Structure and stability of various states of the EuC and EuC2 molecules

B3LYP level density functional theory （DFT） and multiconfiguration self-consistent-field （MCSCF） level ab initio method calculations have been performed on the basis of relativistic effective core potentials to investigate the nature of EuC and EuC2 molecules. The computed results indicate that the ground states of EuC and EuC2 are ^12∑^＋ and SA2, respectively. Dissociation potential energy curves of the low-lying electronic states of EuC have been calculated using the MCSCF method, and the same level calculation on EuC2 indicates that the dissociation energy of EuC2 of ground state compares well with the available experimental data. The bond characteristic is also discussed using Mulliken populations.     

Prediction of binding bond energy between phosphorous-based ionic liquids and CO2. Assessment of the CO2–anion interactions

The absorption of carbon dioxide (CO₂) in phosphorous-based ionic liquids was studied theoretically by the molecular modeling ab initio density functional theory (dispersion-corrected B3LYP) and second-order M?ller-Plesset perturbation methods. Several types of phosphate- and phosphite-based anions were employed and the calculation results were compared with recent published papers. The interaction energy between CO₂ and anion, following the result of Bhargava and Balasubramanian, was calculated in order to have a better understanding on the effect of different functional groups on the interaction between CO₂ and anion. The computational results indicated that the molar volume of the anion molecules played an important role on the absorption mechanism of CO₂ due to the CO₂-philicity of carbonyl and alkyl groups.     

Correlated energy disposal and scattering dynamics of the Cl CD4(ν3 = 2) reaction

Molecular chlorine, methane and helium are co-expanded into the extraction region of a Wiley-McLaren time-of-flight spectrometer. After preparing the first overtone of the antisymmetric stretch (ν3 = 2) with direct IR excitation, the reaction is initiated by photolysing Cl2 with 355 nm light to produce mono-energetic Cl atoms with a translational energy of 0.18 eV. The CD3 and DCl products are state-selectively detected via resonance enhanced multiphoton ionization (REMPI) and analysed with the core-extraction technique. Unusual structure in the 3pz CD3 REMPI spectrum suggests the presence of a previously unobserved transition, which we assign to the stretch-bend combination ( [image omitted]) band. The product correlated energy disposal and the scattering distributions are compared with the same quantities for the Cl + CH4(ν3 = 2) reaction and found to be similar, although subtle differences are observed. The results for the Cl + CD4(ν3 = 2) reaction support a localized chemistry model in which the Cl atom interacts with a single C-D oscillator and leaves the CD3 methyl radical as a spectator.     

Hypervirial treatment of centrifugal distortion of 2Π energy levels

An analytical perturbation has been carried out, using a hypervirial scheme, of the wave equation with Morse potential and additional perturbations involving powers of [1-exp(-aq)]. The centrifugal distortion contributions to rovibrational energies are derived for diatomic molecules and compact formulae are obtained for successive radial derivatives of the spin-orbit function. Numerical applications are described to the X²Π states of several molecules.     

Investigation of analytical harmonic frequency and potential energy function,vibrational levels for the X^2∑^＋ and A^2Л states of CN radical

This paper calculates the equilibrium structure and the potential energy functions of the ground state （X^2∑^＋） and the low lying excited electronic state （A^2Л） of CN radical are calculated by using CASSCF method. The potential energy curves are obtained by a least square fitting to the modified Murrell-Sorbie function. On the basis of physical theory of potential energy function, harmonic frequency （ωe） and other spectroscopic constants （ωeχe, βe and αe） are calculated by employing the Rydberg-Klei-Rees method. The theoretical calculation results are in excellent agreement with the experimental and other complicated theoretical calculation data. In addition, the eigenvalues of vibrational levels have been calculated by solving the radial one-dimensional SchrSdinger equation of nuclear motion using the algebraic method based on the analytical potential energy function.     

Measurements of the line strengths,N2− and O2-broadened half-widths in the ν3, ν1+2ν2 and 2ν1 bands of 14N2 16O at room temperature

The line strengths, N₂? and O₂-broadened half-widths in the ν₃, ν₁+2ν₂ and 2ν₁ bands of ¹⁴N₂ ¹⁶O were determined from spectra obtained by a high-resolution Fourier transform spectrometer at room temperature. The squared vibrational transition dipole moments and the coefficients of the Herman–Wallis factor were also determined for these bands. The squared vibrational transition dipole moments for these bands agreed with the values of HITRAN and high-resolution experiments within 6%. The N₂? and O₂-broadened half-widths were in agreement with the results of recent high-resolution experiments. The air-broadened half-widths were calculated using the smoothed N₂? and O₂-broadened half-widths and compared with the compiled values in the HITRAN database.     

Theoretical calculation of energy levels and radiative lifetimes of T1 I

Considering the perturbation,the results of theoretical calculation of five Rydberg series energy levels 6s~2ns~2S_(1/2)(n=7-20),6s~2nd~2D_(3/2)(n=6-20),6~s2nd~2D_(5/2)(n=6-20),6s~2np~2p_(1/2)~0(n=7-20),and 6s~2np~2p_(3/2)~0(n=7-20)for T11 are presented using the weakest bound electron potential model(WBEPM) theory.Furthermore,the radiative lifetimes of this five series are also calculated.The calculated values of energy levels and lifetimes are in good agreement with the experimental results.     

Line intensities in the ν1 + 2ν2, 2ν2 + ν3, 2ν1, ν1 + ν3, 2ν3, and ν1 + ν2 + ν3 − ν2 bands of H216O,between 6300 and 7900 cm−1

Using Fourier transform spectra, the intensities of 428 weak lines belonging to the ν₁ + 2ν₂, 2ν₂ + ν₃, 2ν₁, ν₁ + ν₃, 2ν₃, and ν₁ + ν₂ + ν₃ − ν₂ bands of the H₂¹⁶O molecule have been measured, between 6300 and 7900 cm⁻¹, with an average uncertainty of 7%.     

Excitation of isomeric states in the (γ,n), (n, 2n), and (γ, 2n) reactions on the 113In nucleus

The induced-activity method was used to measure the isomeric ratio of the yields of the (γ, n), (n, 2n), and (γ, 2n) reactions on the ¹¹³In nucleus. The energy dependence of the isomeric ratios of the yields of the photonuclear reactions ¹¹³In(γ, n)^112m,g In and ¹¹³In(γ, 2n)^111m,g In is studied in the energy range of 12–35 MeV.     

Determination of the Rydberg D and F° energy levels of Cs-like ions by the method of interpolation of relativistic quantum defects

Data are presented that allow one to determine the energy values of the Rydberg levels nD _3/2, nD _5/2, nF _5/2°, and nF _7/2° for ions of the cesium isoelectronic sequence by the method of interpolation of rela- tivistic quantum defects in the Dirac-Fock approximation. To improve agreement with the experimental data, it is proposed to use an empirical correction for the quantum defect. The obtained energy values are compared with the experimental data. The anomalous behavior of the quantum defects of the nf levels is discussed. The calculations are carried out for ten ions of the cesium isoelectronic sequence.     

A high-resolution study of the ν3 and 2ν80 bands of propyne

The ν₃ and 2ν₈⁰ parallel bands of propyne (methyl acetylene) at 2137.88 and 2066.33 cm⁻¹ have been studied at 0.006 cm⁻¹ resolution. Their Fermi resonance and interaction with the ν₈ + 2ν₉, ν₇ + ν₉, and ν₈ + ν₉ + ν₁₀ levels have been investigated. Molecular constants were determined from the assignment of 1150 lines. However, the rms error of 0.0028 cm⁻¹ showed the presence of additional perturbations which cannot be uniquely identified.     

Analysis of the High-Resolution Infrared Spectrum of the PHD2 Molecule: ν1 and 2ν1 Bands

The results of investigation into the infrared spectra of the PHD₂ molecule including the ₁ fundamental band centered at 2324.005 cm^–1 (with a resolution of 4.2·10^–3 cm^–1) and the first 2₁ valence overtone centered at 4563.634 cm^–1 (with a resolution of 8.8·10^–3 cm^–1) are given in the present paper. Based on an analysis of the results obtained, 1340 and 1020 lines are referred to the ₁ and 2₁ bands, respectively. This data are used to calculate 316 and 248 vibrational-rotational energies of the (100000) and (200000) excited vibrational states, respectively. Since both bands can be considered as isolated, we take advantage of the Watson Hamiltonian (the reduction A in the I ^r representation) to describe their rotational structure. The calculated spectroscopic parameters of the examined states of the PHD₂ molecule correlate well with each other and with the corresponding parameters of the ground vibrational state.     

An investigation of the interaction between close-lying 2σ and 2II states of diatomic molecules

A perturbation calculation of the interaction between close-lying ²σ and ²II states of diatomic molecules has been carried out to the fourth order. The formula for the spin-splitting of the ²σ states thus obtained has been found to yield a proper explanation for the large anomalies encountered in the spinsplitting of the B ²σ states of the hydrides and deuterides of Ca, Sr and Ba. Especially for CaH, CaD, SrH and SrD good agreement between theoretical and fitted values has been found for the higher-order correction terms to the spin-splitting.     

Measurements of air and noble-gas broadening and shift coefficients of the methane R3 triplet of the 2ν3 band

By using a tunable diode laser spectrometer with one absorption White cell for low pressure and one photoacoustic cell for high pressure, line shape parameters of the R3 triplet of the 2ν₃ band of methane at 1.65 μm were measured. The absorption line was recorded by using the wavelength modulation spectroscopy technique with first harmonic detection. The broadening and shift coefficients were obtained by fitting the first harmonic absorption signal while varying the pressure of different perturbing gases: air and noble gases (helium, neon, argon, krypton and xenon). We present here the results for the R3 triplet. The observed shift and broadening coefficients behaviors are discussed. Received: 17 November 2000 / Revised version: 19 February 2001 / Published online: 27 April 2001